"First time you've had me aboard," he said. "Comfortable. Very."

"Thanks…Cream? Sugar?"

"Yes. Both."

We settled back with our steaming mugs and I asked, "What have you got?"

"One case involving two problems," he said. "One of them sort of falls within my area of competence. The other does not. I was told that it is an absolutely unique situation and would require the services of a very special specialist."

"I'm not a specialist at anything but keeping alive."

His eyes came up suddenly and caught my own.

"I had always assumed that you knew an awful lot about computers," he said.

I looked away. That was hitting below the belt. I had never held myself out to him as an authority in that area, and there had always been a tacit understanding between us that my methods of manipulating circumstance and identity were not open to discussion. On the other hand, it was obvious to him that my knowledge of the system was both extensive and intensive. Still, I didn't like talking about it. So I moved to defend.

"Computer people are a dime a dozen," I said. "It was probably different in your time, but these days they start teaching computer science to little kids their first year in school. So sure, I know a lot about it. This generation, everybody does,"

"You know that is not what I meant," he said. Haven't you known me long enough to trust me a little more than that? The question springs solely from the case at hand. That's all."

I nodded. Reactions by their very nature are not always appropriate, and I had invested a lot of emotional capital in a heavy-duty set. So, "Okay, I know more about them than the school kids," I said.

"Thanks. That can be our point of departure." He took a sip of coffee. "My own background is in law and accounting, followed by the military, military intelligence, and civil service, in that order. Then I got into this business. What technical stuff I know I've picked up along the way, a scrap here, a crash course there. I know a lot about what things can do, not so much about how they work. I did not understand the details on this one, so I want you to start at the top and explain things to me, for as far as you can go. I need the background review, and if you are able to furnish it I will also know that you are the man for the job. You can begin by telling me how the early space-exploration robots worked, like, say the ones they used on Venus."

"That's not computers," I said, "and for that matter, they weren't really robots. They were telefactoring devices."

"Tell me what makes the difference."

"A robot is a machine which carries out certain operations in accordance with a program of instructions. A telefactor is a slave machine operated by remote control The telefactor functions in a feedback situation with its operator. Depending on how sophisticated you want to get, the links can be audiovisual, kinesthetic, tactile, even olfactory. The more you want to go in this direction, the more anthropomorphic you get in the thing's design.

"In the case of Venus, if I recall correctly, the human operator in orbit wore an exoskeleton which controlled the movements of the body, legs, arms, and hands of the device on the surface below, receiving motion and force feedback through a system of airjet transducers. He had on a helmet controlling the slave device's television camera, set, obviously enough, in its turret, which filled his field of vision with the scene below. He also wore earphones connected with its audio pickup. I read the book he wrote later. He said that for long stretches of time he would forget the cabin, forget that he was at the boss end of a control loop, and actually feel as if he were stalking through that hellish landscape. I remember being very impressed by it, just being a kid, and I wanted a super-tiny one all my own, so that I could wade around in puddles picking fights with microorganisms."

"Why?"

"Because there weren't any dragons on Venus. Anyhow, that is a telefactoring device, a thing quite distinct from a robot."

"I'm still with you," he said, and "Now tell me the difference between the early telefactoring devices and the later ones."

I swallowed some coffee.

"It was a bit trickier with respect to the outer planets and their satellites," I said. "There, we did not have orbiting operators at first. Economics, and some unresolved technical problems. Mainly economics. At any rate, the devices were landed on the target worlds, but the operators stayed home. Because of this, there was of course a time lag in the transmissions along the control loop. It took a while to receive the on-site input, and then there was another time lapse before the response movements reached the telefactor. We attempted to compensate for this in two ways: the first was by the employment of a single wait-move, wait-move sequence; the second was more sophisticated and is actually the point where computers come into the picture in terms of participating in the control loop. It involved the setting up of models of known environmental factors, which were then enriched during the initial wait-move sequences. On this basis, the computer was then used to anticipate short-range developments. Finally, it could take over the loop and run it by a combination of 'predictor controls' and wait-move reviews. It still had to holler for human help, though, when unexpected things came up. So, with the outer planets, it was neither totally automatic nor totally manual, nor totally satisfactory, at first."

"Okay," he said, lighting a cigarette. "And the next step?"

"The next wasn't really a technical step forward in telefactoring. It was an economic shift. The pursestrings were loosened and we could afford to send men out. We landed them where we could land them, and in many of the places where we could not, we sent down the telefactors and orbited the men again. Like in the old days. The time-lag problem was removed because the operator was on top of things once more. If anything, you can look at it as a reversion to earlier methods. It is what we still often do, though, and it works."

He shook his head.

"You left something out between the computers and the bigger budget." I shrugged.

"A number of things were tried during that period, but none of them proved as effective as what we already had going in the human-computer partnership with the telefactors."

"There was one project," he said, "which attempted to get around the time-lag troubles by sending the computer along with the telefactor as part of the package. Only the computer wasn't exactly a computer and the telefactor wasn't exactly a telefactor. Do you know which one I am referring to?"

I lit a cigarette of my own while I thought about it, then, "I think you are talking about the Hangman," I said.

"That's right and this is where I get lost. Can you tell me how it works?"

"Ultimately, it was a failure," I told him.

"But it worked at first."

"Apparently. But only on the easy stuff, on Io. It conked out later and had to be written off as a failure, albeit a noble one. The venture was overly ambitious from the very beginning. What seems to have happened was that the people in charge had the opportunity to combine vanguard projects, stuff that was still under investigation and stuff that was extremely new. In theory, it all seemed to dovetail so beautifully that they yielded to the temptation and incorporated too much. It started out well, but it fell apart later."

"But what all was involved in the thing?"

"Lord! What wasn't? The computer that wasn't exactly a computer…Okay, well start there. Last century, three engineers at the University of Wisconsin, Nordman, Parmentier, and Scott, developed a device known as a superconductive tunnel-junction neuristor. Two tiny strips of metal with a thin insulating layer between. Supercool it and it passed electrical impulses without resistance. Surround it with magnetized material and pack a mass of them together, billions, and what have you got?" He shook his head.